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Encyclopedia > Miocene

The Miocene Epoch is a period of time that extends from about 23.03 to 5.332 million years before the present. As with other older geologic periods, the rock beds that define the start and end are well identified but the exact dates of the start and end of the period are uncertain. The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words μείων (meioon, less) and καινός (kainos, new) and means "less recent" because it has 18% (less than the Pliocene) of modern sea invertebrates. The Miocene follows the Oligocene Epoch and is followed by the Pliocene Epoch. The Miocene is the first epoch of the Neogene Period. The geologic time scale is used by geologists and other scientists to describe the timing and relationships between events that have occurred during the history of the Earth. ... In geology, a period or age is a time span of many millions of years that are assumed to have had similar characteristics. ... Charles Lyell Sir Charles Lyell (November 14, 1797 – February 22, 1875), British geologist, and popularizer of uniformitarianism. ... The Pliocene epoch (spelled Pleiocene in some older texts) is the period in the geologic timescale that extends from 5. ... The Oligocene epoch is a geologic period of time that extends from about 34 million to 23 million years before the present. ... Neogene Period is a unit of geologic time consisting of the Miocene, Pliocene, Pleistocene, and Holocene epochs. ...


The Miocene boundaries are not set at an easily identified worldwide event but rather at regional boundaries between the warmer Oligocene and the cooler Pliocene.

Contents

Subdivisions

The Miocene faunal stages from youngest to oldest are typically named according to the International Commission on Stratigraphy: Faunal stages are a subdivision of geologic time used primarily by paleontologists who study fossils rather than by geologists who study rock formations. ... The International Commission on Stratigraphy concerns itself with stratigraphy on a global scale. ...

Messinian (7.246 – 5.332 mya)
Tortonian (11.608 – 7.246 mya)
Serravallian (13.65 – 11.608 mya)
Langhian (15.97 – 13.65 mya)
Burdigalian (20.43 – 15.97 mya)
Aquitanian (23.03 – 20.43 mya)

These subdivisions within the Miocene are defined by the relative abundance of different species of calcareous nanofossils (calcite platelets shed by brown single-celled algae) and foraminifera (single-celled protists with diagnostic shells). Two subdivisions each form the Early, Middle and Late Miocene. The Messinian period is the last part of the Miocene epoch. ... In astronomy, geology, and paleontology, mya is an acronym for million years ago and is used as a unit of time to denote length of time before the present. ... Millions of Years Categories: Graphical timelines | Geology stubs ... Millions of Years Categories: Graphical timelines | Geology stubs ... Millions of Years Categories: Graphical timelines | Geology stubs ... In the geologic timescale, the Burdigalian is the age of the Miocene epoch of the Neogene period of the Cenozoic era of the Phanerozoic eon that is between 20. ... In the geologic timescale, the Aquitanian is the stage of the Miocene Epoch that is comprehended between 23 million 30 thousand and 20 million 430 thousand years ago, approximatedly. ... Doubly refracting Calcite from Iceberg claim, Dixon, New Mexico. ... Orders Allogromiida Carterinida Fusulinida - extinct Globigerinida Involutinida - extinct Lagenida Miliolida Robertinida Rotaliida Silicoloculinida Spirillinida Textulariida incertae sedis    Xenophyophorea    Reticulomyxa The Foraminifera, or forams for short, are a large group of amoeboid protists with reticulating pseudopods, fine strands that branch and merge to form a dynamic net. ...


In most of North America, faunal stages are defined according to the land mammal fauna (NALMA). They overlap the borders of the Miocene and Oligocene/Pliocene: World map showing North America A satellite composite image of North America. ...

Hemphillian (9 – 4.75 mya); includes much of the Early Pliocene
Clarendonian (11.8 – 9 mya)
Barstovian (15.5 – 11.8 mya)
Hemingfordian (19 – 15.5 mya)
Arikareean (30.5 – 19 mya); includes much of the Oligocene

Californian sites, which are derived from the former Farallon Plate, provide another sequence which also overlaps with the epoch boundaries : Official language(s) English Capital Sacramento Largest city Los Angeles Area  Ranked 3rd  - Total 158,302 sq mi (410,000 km²)  - Width 250 miles (400 km)  - Length 770 miles (1,240 km)  - % water 4. ... The Farallon Plate is an ancient tectonic plate which began subducting as Pangaea broke apart during the Jurassic period. ...

Delmontian (7.5 – 2.9 mya); includes much of the Pliocene
Mohnian (13.5 – 7.5 mya)
Luisian (15.5 – 13.5 mya)
Relizian (16.5 – 15.5 mya)
Saucesian (22 – 16.5 mya)
Zemorrian (33.5 – 22 mya); includes nearly all the Oligocene

Yet other systems are used to describe the Miocene stratigraphy of Japan, Australia and New Zealand.


Climate

Climates remained moderately warm, although the slow global cooling that eventually led to the Pleistocene glaciations continued. The Pleistocene epoch (IPA: ) is part of the geologic timescale. ... A glaciation (a created composite term meaning Glacial Period, referring to the Period or Era of, as well as the process of High Glacial Activity), often called an ice age, is a geological phenomenon in which massive ice sheets form in the Arctic and Antarctic and advance toward the equator. ...


Although a long-term cooling trend was well underway, there is evidence of a warm period during the Miocene when the global climate rivalled that of the Oligocene. The Miocene warming began 21 million years ago and continued until 14 million years ago, when global temperatures took a sharp drop - the Middle Miocene Climate Transition (MMCT). By 8 million years ago, temperatures dropped sharply once again, and the Antarctic ice sheet was already approaching its present-day size and thickness. Greenland may have begun to have large glaciers as early as 7 to 8 million years ago,[citation needed] although the climate for the most part remained warm enough to support forests there well into the Pliocene. The Oligocene epoch is a geologic period of time that extends from about 34 million to 23 million years before the present. ...


Paleogeography

Continents continued to drift toward their present positions. Of the modern geologic features, only the land bridge between South America and North America was absent, although South America was approaching the western subduction zone in the Pacific Ocean, causing both the rise of the Andes and a southward extension of the Meso-American peninsula. Animated, colour-coded map showing the various continents. ... Plates in the crust of the earth, according to the plate tectonics theory Continental drift refers to the movement of the Earths continents relative to each other. ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ... World map showing North America A satellite composite image of North America. ... Planes view of the Andes, Peru. ... The cultural areas of Mesoamerica The term Mesoamérica is used to refer to a geographical region that extends roughly from the Tropic of Cancer in central Mexico down through Guatemala, Belize, Honduras, El Salvador, and Nicaragua to northwestern Costa Rica, and which is characterized by the particular cultural homogeneity...


Mountain building took place in Western North America and Europe. Both continental and marine Miocene deposits are common worldwide with marine outcrops common near modern shorelines. Well studied continental exposures occur in the American Great Plains and in Argentina. World map showing the location of Europe. ... The Great Plains covers much of the central United States, portions of Canada and Mexico. ...


India continued to collide with Asia, creating more mountain ranges. The Tethys Seaway continued to shrink and then disappeared as Africa collided with Eurasia in the Turkish-Arabian region between 19 and 12 mya. Subsequent uplift of mountains in the western Mediterranean region and a global fall in sea levels combined to cause a temporary drying up of the Mediterranean Sea (known as the Messinian salinity crisis) near the end of the Miocene. World map showing the location of Asia. ... A world map showing the continent of Africa Africa is the worlds second-largest and second most-populous continent, after Asia. ... Eurasia African-Eurasian aspect of Earth Eurasia is the Earths largest landmass covering about 21215121321km² compared with the Americas (approximately 42,000,000 km²), Africa (approximately 30,000,000 km²), and Antarctica (approximately 13,000,000 km²). Eurasia comprises the traditional continents of Europe and Asia. ... The Arabian Peninsula The Arabian Peninsula is a mainly desert peninsula in Southwest Asia at the junction of Africa and Asia and an important part of the greater Middle East. ... The Mediterranean Sea is an intercontinental sea positioned between Europe to the north, Africa to the south and Asia to the east, covering an approximate area of 2. ... // The Messinian Salinity Crisis, also referred to as the Messinian Event, is a period when the Mediterranean Sea evaporated partly or completely dry during the Messinian period of the Miocene epoch, approximately 6 million years ago. ...


The global trend was one towards increasing aridity caused primarily by global cooling reducing the ability of the atmosphere to absorb moisture. Uplift of East Africa in the Late Miocene was partly responsible for the shrinking of tropical rain forests in that region, and Australia got drier as it entered a zone of low rainfall in the Late Miocene.  Eastern Africa (UN subregion)  East African Community  Central African Federation (defunct)  geographic, including above East Africa or Eastern Africa is the easternmost region of the African continent, variably defined by geography or geopolitics. ...


Life

Flora

Grasslands underwent a major expansion forests fell victim to a generally cooler and drier climate overall. Grasses also diversified greatly, co-evolving with large herbivores and grazers, including ruminants. Bumblebees and the flowers they pollinate have co-evolved so that both have become dependent on each other for survival. ... This article does not adequately cite its references or sources. ...


Fauna

Both marine and continental fauna were fairly modern, although marine mammals were less numerous. Only in isolated South America and Australia did widely divergent fauna exist. Mammals were also modern, with recognizable wolves, raccoons, horses, beaver, deer, camels, and whales. Fauna is a collective term for animal life. ... Wolf Wolf Man Mount Wolf Wolf Prizes Wolf Spider Wolf 424 Wolf 359 Wolf Point Wolf-herring Frank Wolf Friedrich Wolf Friedrich August Wolf Hugo Wolf Johannes Wolf Julius Wolf Max Franz Joseph Cornelius Wolf Maximilian Wolf Rudolf Wolf Thomas Wolf As Name Wolf Breidenbach Wolf Hirshorn Other The call... Binomial name Equus caballus Linnaeus, 1758 The horse (Equus caballus, sometimes seen as a subspecies of the Wild Horse, Equus ferus caballus) is a large odd-toed ungulate mammal, one of ten modern species of the genus Equus. ... Species C. canadensis C. fiber Beavers are semi-aquatic rodents native to North America and Europe. ... “Fawn” redirects here. ... For other uses, see Camel (disambiguation). ... A Fin Whale The term whale is ambiguous: it can refer to all cetaceans, to just the larger ones, or only to members of particular families within the order Cetacea. ...


Recognizable crows, ducks, auks, grouses and owls appear in the Miocene. By the epoch's end, all or almost all modern families are believed to have been present; the few post-Miocene bird fossils which cannot be placed in the evolutionary tree with full confidence are simply too badly preserved instead of too equivocal in character. Marine birds reached their highest diversity ever in the course of this epoch. Species See text. ... Subfamilies Dendrocygninae Oxyurinae Anatinae Aythyinae Merginae Duck is the common name for a number of species in the Anatidae family of birds. ... Genera Uria Alle Alca Pinguinus Synthliboramphus Cepphus Brachyramphus Ptychoramphus Aethia Cerorhinca Fratercula Extinct genera, see Systematics Auks are birds of the family Alcidae in the order Charadriiformes. ... Genera Tetrao Lagopus Falcipennis Centrocercus Bonasa Dendrapagus Tympanuchus Grouse are from the order Galliformes which inhabit temperate and subarctic regions of the northern hemisphere. ... Families Strigidae Tytonidae Ogygoptyngidae (fossil) Palaeoglaucidae (fossil) Protostrigidae (fossil) Sophiornithidae (fossil) Synonyms Strigidae sensu Sibley & Ahlquist Owls are a group of birds of prey. ... In biological classification, family (Latin: familia, plural familiae) is 1) a rank or 2) a taxon in that rank. ...


Brown algae, called kelp, proliferate, supporting new species of sea life, including otters, fish and various invertebrates. The cetaceans diversified, and some modern genera appeared, such as the sperm whales. The pinnipeds, which appeared near the end of the Oligocene, became more aquatic. Orders Ascoseirales Chordariales Cutleriales Desmarestiales Dictyosiphonales Dictyotales Ectocarpales Fucales Laminariales(kelps) Scytosiphonales Scytothamnales Sphacelariales Sporochnales Syringodermatales Tilopteridales The brown algae or phaeophytes are a large group of multicellular algae, including many notable seaweeds. ... Insert non-formatted text hereLink title Families Alariaceae Chordaceae Laminariaceae Lessoniaceae Phyllariaceae Pseudochordaceae For other uses, see Kelp (disambiguation). ... Genera Amblonyx Aonyx Enhydra Lontra Lutra Lutrogale Pteronura The otter (lutrinae) is a carnivorous aquatic or marine mammal part of the family Mustelidae, which also includes weasels, polecats, badgers, as well as others. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... Invertebrate is a term that describes any animal without a spinal column. ... Genera Kogia Physeter The sperm whale family or simply the sperm whales is the collective name given to three species of whale, the Sperm Whale, the Pygmy Sperm Whale and the Dwarf Sperm Whale. ... Families Odobenidae Otariidae Phocidae Pinnipeds (fin-feet, lit. ...


Perhaps most important were the 100 or so species of apes that lived during this time. They occupied much of the Old World and ranged in size, diet, and anatomy. Due to scanty fossil evidence it is unclear which ape or apes contributed to the modern hominoid clade, but molecular evidence indicates this ape lived from between 15 to 12 million years ago. Families Hylobatidae Hominidae Apes are the members of the Hominoidea superfamily of primates, which includes humans. ... The Old World consists of those parts of Earth known to Europeans, Asians, and Africans before the voyages of Christopher Columbus; it includes Europe, Asia, and Africa (collectively known as Africa-Eurasia), plus surrounding islands. ... Families Hylobatidae Hominidae Apes are the members of the Hominoidea superfamily of primates, including humans. ...


In the oceans, modern sharks appeared at this time. Cetaceans, such as dolphins, whales, and porpoises evolved. Their ancestors the Archaeoceti, however, were becoming less common and eventually became extinct. Orders Carcharhiniformes Heterodontiformes Hexanchiformes Lamniformes Orectolobiformes Pristiophoriformes Squaliformes Squatiniformes Symmoriida(extinct) Shark (superorder Selachimorpha) are fish with a full cartilaginous skeleton[1] and a streamlined body. ... Suborders Mysticeti Odontoceti (see text) The order Cetacea includes whales, dolphins and porpoises. ... Genera See article below. ... A Fin Whale The term whale is ambiguous: it can refer to all cetaceans, to just the larger ones, or only to members of particular families within the order Cetacea. ... Genera Neophocaena Phocoena - Harbor porpoise Phocoenoides - Dalls porpoise The porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. ... Families and Clades see text Archaeoceti, or ancient whales are a paraphyletic group of cetaceans that gave rise to Autoceti - the new cetaceans. ...


Oceans

The oceans continued to cool as the poles were transformed into glaciers. A glacier is a large, persistent body of ice, formed largely of compacted layers of snow, that slowly deforms and flows in response to gravity. ...


See also

Neogene period
Miocene Pliocene
Aquitanian | Burdigalian | Langhian
Serravallian | Tortonian | Messinian
Zanclean | Piacenzian
→ Quaternary

// For other uses, see time scale. ... List of fossil sites: // Afar Depression, Ethiopia, Pliocene Awash River, Afar Depression, Ethiopia, Australopithecus afarensis, Lucy, Pliocene, 3. ... Neogene Period is a unit of geologic time consisting of the Miocene, Pliocene, Pleistocene, and Holocene epochs. ... The Pliocene epoch (spelled Pleiocene in some older texts) is the period in the geologic timescale that extends from 5. ... In the geologic timescale, the Aquitanian is the stage of the Miocene Epoch that is comprehended between 23 million 30 thousand and 20 million 430 thousand years ago, approximatedly. ... In the geologic timescale, the Burdigalian is the age of the Miocene epoch of the Neogene period of the Cenozoic era of the Phanerozoic eon that is between 20. ... Millions of Years Categories: Graphical timelines | Geology stubs ... Millions of Years Categories: Graphical timelines | Geology stubs ... Millions of Years Categories: Graphical timelines | Geology stubs ... The Messinian period is the last part of the Miocene epoch. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... In the geologic timescale, Piacenzian is an ICS stage, part of the Pliocene epoch of the Neogene period. ... The Quaternary Period is the geologic time period from the end of the Pliocene Epoch roughly 1. ...

References

  • Ogg, Jim; (2004): Overview of Global Boundary Stratotype Sections and Points (GSSP's). HTML fulltext. Retrieved 2006-APR-30.
  • Rohde, Robert A. (2005): GeoWhen Database. Retrieved 2006-SEP-23.
  • Cox, C. Barry, and Moore, Peter D., Biogeography. An ecological and evolutionary approach. Fifth edition, Cambridge 1993 (1998)

External links

Wikimedia Commons has media related to:
Miocene

  Results from FactBites:
 
Miocene epoch. The Columbia Encyclopedia, Sixth Edition. 2001-05 (477 words)
Miocene rocks are found along the Atlantic as far N as Martha’s Vineyard, but the series, everywhere thin, is thickest and least interrupted from New Jersey to Maryland.
The mammalian life of the Miocene was marked by further stages in the development of the horse, by the multiplication and final extinction of the giant hogs, and by the appearance of the mastodons, raccoons, and weasels.
In the Miocene a distinct cooling of the climate resulted in the reduction of forests and an increase in grassy plains.
AllRefer.com - Miocene epoch (Geology And Oceanography) - Encyclopedia (547 words)
Miocene rocks are found along the Atlantic as far N as Martha's Vineyard, but the series, everywhere thin, is thickest and least interrupted from New Jersey to Maryland.
The mammalian life of the Miocene was marked by further stages in the development of the horse, by the multiplication and final extinction of the giant hogs, and by the appearance of the mastodons, raccoons, and weasels.
In the Miocene a distinct cooling of the climate resulted in the reduction of forests and an increase in grassy plains.
  More results at FactBites »

 
 

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